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June 20, 2005

MRI Shows Up Brain Differences in Bipolar Disorder

by Sam Savage

NEW YORK -- Efforts to define the abnormally activated areas in the brains of people with bipolar disorder could lead to new drug treatments and better coping strategies, investigators reported at the International Conference on Bipolar Disorder in Pittsburgh.

People with bipolar disorder suffer from extreme swings in mood, from depression to mania. Dr. Stephen M. Strakowski and colleagues used functional MRI, which measures levels of metabolic activity in different areas, to examine the brains of 10 patients with bipolar disorder while they were in a manic episode and 15 healthy people.

The study participants performed a "stop-signal task," in which they were instructed to respond to projected letters depending on the letter color. The test provides a measure of impulse control, Strakowski explained in an interview with Reuters Health.

During the test, bipolar patients exhibited increased activation in a "distributed network of brain regions known to involve the control of emotion and emotional expression," Strakowski said. His group found that these mood networks are connected with the cognitive networks, "so when mood networks are overactivated they interfere with cognition," leading to reduced impulse control.

The researchers looked at areas of the posterior brain typically involved in attentional processes in healthy people. These areas become activated as attentional tasks become more difficult.

Bipolar patients seem to have these areas activated at baseline, "suggesting that they try to recruit these compensatory areas to manage the interference from the emotional network," the researcher noted.

This means that bipolar patients tend not to trade speed for accuracy as tasks become more complicated, he continued. "They won't slow down to do better."

He hopes that their findings will lead to new therapeutic approaches for bipolar disorder, such as helping patients learn how to delay reactions so that decision-making is more functional.

These findings will also assist the researchers in the next stage of their work, Strakowski said. "The next step is to use other imaging methods like magnetic resonance spectroscopy to define neurochemical abnormalities that underlie these activation abnormalities."

Such neurochemical abnormalities could provide direct targets for drug development.